Method for the production of a fiber web

ABSTRACT

A method for the production of a fiber web from a fiber stock suspension including a filler, including the steps of: selecting at least one size of at least one filler particles for a predetermined color of the fiber web, including at least one filler particles in the filler, adding at least one filler including at least one filler particles of at least one size in the fiber stock suspension and producing the fiber web in the predetermined color.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for the production of afiber web, specifically a paper or cardboard web, from a fiber stocksuspension.

[0003] 2. Description of the Related Art

[0004] The current trend is to produce paper having brightness valuesthat are as high as possible. These brightness values may be achieved byintroducing fillers such as calcium carbonate, or ground calciumcarbonate into the fiber stock suspension.

[0005] The loading with an additive, i.e. a filler, may occur forexample through a chemical precipitation reaction, that is specificallythrough a so-called “fiber loading™” process, such as described in theprior art documentation U.S. Pat. No. 5,223,090 and U.S. Pat. No.6,355,138, among others. During such a “fiber loadingTM” process atleast one additive, specifically a filler, is deposited on the moistenedfiber surfaces of the fiber material. The fibers may, for example, beloaded with calcium carbonate. To this end, calcium oxide and/or calciumhydroxide are added to the moist disintegrated fiber material in such amanner, whereby at least a portion of these additives associates withthe water that is contained in the fiber material. The fiber materialtreated in this manner is subsequently supplied with carbon dioxide.

[0006] What is needed in the art is a method for loading a fiber webwith an additive to improve brightness and that would provide as simpleand as reliable a method as possible for the production of fiber webs invarious colors.

SUMMARY OF THE INVENTION

[0007] The present invention provides a method for the production of afiber web, specifically a paper or cardboard web, from a fiber stocksuspension containing a filler, whereby the size of the filler particlesis selected with the particular objective of producing a fiber web of apredetermined color.

[0008] The present invention comprises, in one form thereof, a methodfor the production of a fiber web from a fiber stock suspensionincluding a filler, including the steps of: selecting at least one sizeof at least one filler particles for a predetermined color of the fiberweb, including at least one filler particles in the filler, adding atleast one filler including at least one filler particles of at least onesize in the fiber stock suspension and producing the fiber web in thepredetermined color.

[0009] An advantage of the present invention is a simple and reliablemethod for the production of fiber webs in various colors.

[0010] Another advantage is the production of fiber webs in variouscolors with improved brightness.

[0011] Yet another advantage is the fact that the dispersion andreflection of light is dependent upon the respective particle size.

DETAILED DESCRIPTION OF THE INVENTION

[0012] According to a preferred practical arrangement of the methodaccording to the present invention, filler particles of one and the samesize are utilized in order to produce the color of the fiber web. Inthis instance the color produced by the relevant particle sizeconstitutes the actual color of the fiber web that is visible from thesurface.

[0013] According to an advantageous alternative arrangement, fillerparticles of varying sizes are utilized whereby the different particlesizes are selected so that the color of the fiber web results from thedifferent colors produced by the different particle sizes. The visibleexterior color of the fiber web therefore, results from two or moreprimary colors produced by the respective particle sizes. Specificallythree different particle sizes may be used in this process, and thedifferent particle sizes selected so that three primary colors areproduced from which the color of the fiber web results. The utilizedvolume of fillers of a specific particle size is controlled and/oradjusted to advantage. Specifically, the ratio of the utilized fillervolumes of varying particle sizes can also be controlled and/oradjusted.

[0014] According to a functional practical arrangement of the method inaccordance with the present invention, the throughput of at least onepartial suspension stream containing filler of a certain particle sizeis controlled and/or adjusted. Specifically, the relationship of thethroughputs of two or more partial suspension streams containing fillersof varying particle sizes can also be controlled and/or adjusted.

[0015] According to an effective arrangement of the method in accordancewith the present invention, several fiber webs containing fillers ofvarying particle sizes are produced, and the varying particle sizesselected with the objective that the color of the finished fiber webwill be a result of the different colors produced by the varyingparticle sizes. Specifically, several headboxes may be used whosepartial suspension streams contain filler of varying particle sizes. Theheadbox throughputs and/or the filler content of the partial suspensionstreams can be controlled and/or adjusted.

[0016] Advantageously three headboxes are utilized in order to producethree primary colors through three different filler particle sizes,resulting in the color of the fiber web.

[0017] In order to produce the filler particles, a chemicalprecipitation reaction is effectively triggered and/or a refiningprocess carried out. Basically however, any other desired manufacturingprocess is also feasible. The filler can consist specifically of one orseveral of the following materials: precipitator, synthetic material,calcium carbonate, talc, TiO₂, silica and/or similar materials.

[0018] According to a preferred practical arrangement of the method inaccordance to the present invention, the fiber suspension is loaded withfiller through a chemical precipitation reaction, whereby especiallycrystalline precipitator particles are produced. The precipitator mayfor example be calcium carbonate.

[0019] It is also particularly advantageous if calcium oxide and/orcalcium hydroxide is added to the fiber stock suspension for the purposeof loading the fibers, and if the precipitation is triggered bysupplying carbon dioxide to the fiber suspension.

[0020] When loading the fibers with filler, calcium carbonate (CaCO₃)can for example be deposited at the moistened fiber surfaces by addingcalcium oxide (CaO) and/or calcium hydroxide (Ca(OH)₂) to the moistfiber material, whereby at least a portion of this can associate withthe water of the fiber volume. Carbon dioxide (CO₂) can then beintroduced to the treated fiber material.

[0021] The term “moistened fiber surfaces” may encompass all moistenedsurfaces of the individual fibers. This specifically also encompassesthe instance where the fibers are loaded with calcium carbonate or anyother desired precipitator on their outer surface as well as in theirinterior (lumen).

[0022] Accordingly, the fibers may for example be loaded with the fillercalcium carbonate, whereby the deposit onto the moistened fiber surfacesoccurs through a so-called “fiber loading™” process, as described in theprior art documents U.S. Pat. No. 5,223,090 and U.S. Pat. No. 6,355,138.In this “fiber loading™” process the carbon dioxide reacts, for example,with the calcium hydroxide to water and calcium carbonate. The calciumhydroxide may be introduced to the fiber stock suspension in liquid orin dry form.

[0023] Specifically a refining process can produce the appropriateparticle size.

[0024] A preferred practical arrangement of the method according to thepresent invention distinguishes itself in that the fiber stocksuspension is loaded with filler through a chemical reaction and in thatthe fibers that are loaded with filler are refined in order to producean appropriate filler particle size.

[0025] In certain instances it may be advantageous if a chemical coloris used additionally as a brightener. Production of paper in differentcolors is therefore possible for example, by utilizing particles whosesize is selected so that for the production of a certain color in thefinished paper, a respective color of the visible light is reflected.

[0026] The particles that are present in the finished product may forexample be produced by a precipitation reaction, by refining and/or byanother production process. The utilized material may, for example, be aprecipitator or a synthetic material, calcium carbonate, talc, TiO₂,silica and/or a similar material.

[0027] The particle size is fundamental to achieving optimum opacity aswell as the desired color. A high opacity or brightness is achieved whenthe color spectrum of the visible light is well dispersed. If the entirecolor spectrum is absorbed, the resulting color will be black. If thefiller particle size is below a value of specifically 0.2 to 0.5 μm, thetendency is toward achieving a higher transparency and a higher gloss.

[0028] In order to obtain colored paper, the particle size of the fillermust be in a range in which only one color of the visible light isreflected. The paper then possesses a resulting color that iscomplimentary to the absorbed color. If for example, a filler particleabsorbs the color blue, the resulting color will be yellow. If a fillerparticle is produced which absorbs only one color, then the paper willbe in the complimentary color.

[0029] If the paper contains two filler particles, or more precisely twofiller types that differ in their particle size, where the one particleor the one filler type absorbs for example the color blue and the otherone absorbs the color yellow, then the resulting paper color will begreen.

[0030] Obviously, any other examples of the method according to theinvention would also be feasible.

[0031] Viewed physically, color is an optical phenomenon that captures acertain frequency range of the visible light. Light is known to be aform of electromagnetic radiation that transmits at the velocity oflight. Color is a subjective immaterial sensation that occurs when lightenters the eyes.

[0032] The visible spectrum of light has a wavelength of 400 to 800 m,whereby certain color impressions occur at certain wavelength ranges, asindicated in the table below: Wave length range Color impression 800-605red 605-595 orange 595-580 yellow 580-560 yellow-green 560-500 green500-490 bluish-green 490-480 green-blue 480-435 blue 435-400 violet

[0033] White light is not a color in the physical sense. It doeshowever, show a mixture of all above referenced colors. If one color ofthe visible light is filtered out, the complimentary color remains asindicated in the table below: Filtered out color Complimentary colorBlue Yellow Red Cyan Green Magenta

[0034] Basically, a color can also be produced through a combination ofvarious colors, as indicated in the following examples: Resulting ColorOriginal colors White = Red + Green + Blue Yellow = Red + Green Magenta= Red + Blue Cyan = Green + Blue

[0035] Basically, color can originate in various ways. Chemical colorsfor example, find their origin in colored substances, atoms andespecially in molecules that selectively absorb the sources of light,whereby the color of the atoms or molecules is complementary to thefiltered out light. Structural colors result through refraction,reflection, dispersion and interference.

[0036] For the production of colors according to the present inventionthrough correlative particle sizes, and particularly for utilization ofthe so-called “fiber loadingTM” process the dispersion and reflection isof particular interest. In contrast, refraction is used primarily inoptical devices. Interference or superposition of waves is also excludedin this instance.

[0037] Light is dispersed on very small particles such as for exampledust, in other words, it is reflected in all directions. The dispersioneffect depends greatly on the wavelength. Higher frequencies withshorter wavelengths therefore, are dispersed more strongly. Blue lightfor example, is dispersed approximately ten times more strongly than redlight.

[0038] In the case of a medium consisting of extremely small particles,the blue light is dispersed or filtered out first, and then the yellowlight. A white light beam changes its color from white to yellow andthen to red.

[0039] In the application of, for example, a paper containing fillers,white paper is created when the filler particles reflect the entirespectrum colors, resulting in white light. White paper therefore iscreated if the filler particles are of appropriately different sizes.Transparent paper is created when the light can pass unimpeded throughthe paper, that is, if light is possibly reflected but, however, nolight sources of certain size are filtered out. If a filler particle isproduced that filters out a certain wavelength of the visible light,then the paper will appear in the complimentary color. If for example,blue is filtered out, then the paper will appear in the color yellow.

[0040] If for example different layers are contained in a certain papertype, that respectively filter out a certain wavelength of light, andthat are additively mixed, then basically, any desired paper color canbe selected. In one example of the method according to the presentinvention, the coating processes that were hitherto used for coloring ofthe paper are superfluous. A pre-condition for this is that the fillerpigments only filter out the respective color, irrespective of whetherthey were produced by the so-called “fiber loading™” process or byanother manufacturing process. This may signify for example, that therespective headbox must be controlled and/or adjusted to an optimum withregard to its throughput and with regard to the filler content. Thissignifies that, for example, three headboxes with fillers of differentparticle sizes containing a respective primary color may be utilized, inorder to cover the entire color range.

[0041] A possible gray cast in the produced paper colors may be avoidedby additionally using chemical colors in lower volumes as brighteningagents.

[0042] Basically, other desired arrangements of the method according tothe invention are also feasible.

[0043] While this invention has been described as having a preferreddesign, the present invention can be further modified within the spiritand scope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A method for the production of a fiber web from afiber stock suspension including a filler, comprising the steps of:selecting at least one size of at least one filler particles for apredetermined color of the fiber web; including at least one said fillerparticles in the filler; adding at least one filler including at leastone said filler particles of at least one said size in the fiber stocksuspension; and producing the fiber web in said predetermined color. 2.The method of claim 1, wherein said method is carried out using a singlesaid size of said filler particles.
 3. The method of claim 1, whereinsaid method is carried out using a plurality of said sizes of saidfiller particles, said plurality of said sizes produces a plurality ofcolors, said predetermined color of the fiber web resulting from saidplurality of colors.
 4. The method of claim 3, wherein said method iscarried out using three different said sizes of said filler particles toproduce three primary colors which results in said predetermined colorof the fiber web.
 5. The method of claim 1, wherein said method iscarried out using at least one volume of said filler particles, eachdistinct said volume corresponding to a distinct said size, at least onesaid volume is at least one of controlled and adjusted.
 6. The method ofclaim 5, wherein said method is carried out using at least one ratio ofat least one said volumes, said ratio is at least one of controlled andadjusted.
 7. The method of claim 1, wherein said method is carried outusing the fiber stock suspension including at least one partialsuspension stream, each distinct said partial suspension streamcorresponding to a distinct said size of said filler particles and athroughput, at least one said throughput is at least one of controlledand adjusted.
 8. The method of claim 7, wherein said method is carriedout using at least one ratio of a plurality of said throughputs, saidratio is at least one of controlled and adjusted.
 9. The method of claim7, wherein said method is carried out using a plurality of headboxes,each said headbox including at least one said partial suspension streamand a headbox throughput, at least one said partial suspension streamincluding a content of said filler of varying said sizes of said fillerparticles, at least one of said headbox throughput and said content areat least one of controlled and adjusted.
 10. The method of claim 9,wherein said method is carried out using three said headboxes to producethree primary colors through three distinct said sizes of said fillerparticles which results in said predetermined color of the fiber web.11. The method of claim 1, wherein said method is carried out producinga finished fiber web including a plurality of the fiber webs, each ofthe fiber webs including said fillers of varying said sizes of saidfiller particles, each said size of said filler particles associatedwith a different color, said sizes selected to produce said finishedfiber web in said predetermined color, resulting from said differentcolors produced by said sizes of said filler particles.
 12. The methodof claim 1, further including the step of producing at least one saidfiller particles by at least one of triggering a chemical precipitationreaction and a refining process, said producing at least one said fillerparticles step is prior to said including step.
 13. The method of claim1, wherein said method is carried out with said filler including atleast one of precipitator, synthetic material, calcium carbonate, talc,TiO₂, silica and similar materials.
 14. The method of claim 1, whereinsaid method is carried out by loading the fiber suspension with saidfiller through a chemical precipitation reaction.
 15. The method ofclaim 14, wherein said chemical precipitation reaction produces acrystalline precipitator particles.
 16. The method of claim 15, whereinsaid precipitator is calcium carbonate.
 17. The method of claim 16,further including the steps of adding at least one of calcium oxide andcalcium hydroxide to the fiber stock suspension, the fiber stocksuspension including fibers, the fibers are loaded by said adding step;and supplying carbon dioxide to the fiber suspension thereby triggeringsaid chemical precipitation reaction.
 18. The method of claim 1, furtherincluding a refining process step to produce a predetermined said sizeof said filler particles.
 19. The method of claim 1, further includingthe steps of loading the fiber stock suspension with said filler througha chemical reaction, the fiber stock suspension including fibers whichare loaded with said filler; and refining the fibers thereby producing apredetermined said size of said filler particles.
 20. The method ofclaim 1, wherein said method is carried out using a chemical color as abrightner.